‘Unknown territory’: Antarctic glaciers melting at rate unprecedented in 5,500 years: study

Image by Angie Agostino from Pixabay
Image by Angie Agostino from Pixabay

“These currently elevated rates of ice melting may signal that those vital arteries from the heart of the West Antarctic Ice Sheet have been ruptured,” said one researcher. “Is it too late to stop the bleeding?”

By Julia Conley, Common Dreams (CC BY-NC-ND 3.0).

The human-caused climate crisis is pushing crucial glaciers in Antarctica to lose ice at a rate not seen in more than 5,000 years, according to a new study published Thursday.

Researchers at the University of Maine, the British Antarctic Survey, and Imperial College London found that the Pine Island and Thwaites glaciers on the West Antarctic Ice Sheet could cause global sea level rise of up to 3.4 meters, or over 11 feet, in the next several centuries due to their accelerated rate of ice loss.

“That the present-day rate of glacier retreat that has doubled over the past 30 years is, indeed, unprecedented.”

The glaciers—one of which, the Thwaites, has been called the “doomsday glacier” by climate scientists because of its potential to raise sea levels—are positioned in a way that allows increasingly warm ocean water to flow beneath them and erode the ice sheet from the base, causing “runaway ice loss,” the University of Maine team said in a statement.

The researchers examined penguin bones and seashells on ancient Antarctic beaches in order to analyze changes in local sea levels since the mid-Holocene period, 5,500 years ago.

Sea levels were higher and glaciers were smaller during the mid-Holocene, as the climate of the planet was warmer than it is today.

Since then, according to the study published in Nature Geoscience, relative sea levels have fallen steadily and the Thwaites and Pine Island glaciers have stayed relatively stable—until recent decades.

Ice loss was likely accelerated just prior to the mid-Holocene, and since then, the rate of relative decrease in sea levels over the past 5,500 years was almost five times smaller than it is in present day, due to “recent rapid ice mass loss,” according to the scientists.

“That the present-day rate of glacier retreat that has doubled over the past 30 years is, indeed, unprecedented,” wrote Caroline Brogan, a science reporter at Imperial College.

With the Thwaites spanning an area of more than 74,000 square miles and the Pine Island glacier spanning more than 62,600 square miles, the rapid ice loss of the two glaciers could cause major rises in sea levels around the globe.

Dylan Rood of Imperial College’s Department of Earth Science and Engineering, a co-author of the study, likened the two glaciers to arteries that have burst.

“These currently elevated rates of ice melting may signal that those vital arteries from the heart of the West Antarctic Ice Sheet have been ruptured, leading to accelerating flow into the ocean that is potentially disastrous for future global sea level in a warming world,” said Rood. “Is it too late to stop the bleeding?”

The study follows increasingly urgent calls from the Intergovernmental Panel on Climate Change, the International Energy Agency, and climate scientists around the world for an end to fossil fuel extraction, which is needed to achieve net-zero carbon emissions by 2050 and limit the average global temperature from rising more than 1.5°C above preindustrial levels.

Scientists have warned that the accelerated melting of the Thwaites glacier is likely irreversible.

“We’re going into unknown territory,” Scott Braddock, a researcher at University of Maine, told Science News. “We don’t have an analog to compare what’s going on today with what happened in the past.”

Antarctica Reveals Greater Urgency to Act on Climate Change

The more we learn about Antarctica, the greater the urgency to act on climate change.

Photo by Jay Ruzesky on Unsplash
Photo by Jay Ruzesky on Unsplash

By John Letzing, Digital Editor, Strategic Intelligence, World Economic Forum (Public License).

  • A number of troubling discoveries have been made related to Antarctica.
  • Reports point to record ice shelf melt contributing to sea level rise.
  • Curbing emissions could limit the impact of warming on the continent.

In the pitch-black depths beneath 900 metres of Antarctic ice shelf, scientists recently made a curious discovery: something’s living down there.

The detection of sponges and other “unidentifiable” animals that defy established science is just one in a steady stream of revelations about a forbidding region. Frequently, these insights help build a stronger case for doing more to combat climate change.

Antarctica may be remote and desolate, but it could affect us all relatively soon. Sea levels are now expected to rise more quickly than had been anticipated as recently as 2019, and melting Antarctic glaciers and ice sheets are a contributing factor. The continent has been losing an estimated 150 billion metric tons of ice every year since 2002.

According to results published last week of a study that strapped sensors to sealsrapidly melting Antarctic glaciers are changing nearby ocean water more than realized – with implications for the climate and future sea level rise. A study published not long before that suggested the second-biggest ice shelf on the Antarctic peninsula experienced record melting during the 2019-2020 summer season.

Last year, it was discovered that the ice shelves making up about three-quarters of Antarctica’s coastline, and helping to hold glaciers in place, are melting faster than they’re being replenished. Ultimately, the continent holds enough ice to raise sea levels by 60 metres. Since 1880, global mean sea level has risen by only about 24 centimetres.

As ice departs from Antarctica it can be lethal; a massive iceberg that broke off an ice shelf more than three years ago was bearing down on South Georgia Island and its population of penguins before recently breaking up. Experts say a changing climate is pushing more ice to Antarctica’s edges, where it can encounter warming water and snap off.

Cast Adrift: Tracked Antarctic icebergs at least 15 nautical miles (27.8 km) long as of 5 March, including a remnant of A68A - the iceberg that threatened South Georgia Island.
Cast Adrift: Tracked Antarctic icebergs at least 15 nautical miles (27.8 km) long as of 5 March, including a remnant of A68A – the iceberg that threatened South Georgia Island.
Image: World Economic Forum

Earlier this month, an iceberg bigger than New York City broke off the Brunt Ice Shelf in Antarctica. Scientists say this was part of a natural process and didn’t have direct ties to climate change – though such “calving” events have become increasingly frequent.

Antarctica recorded its hottest days on record slightly more than a year ago, but conditions remain far from ideal for human activity (they are, however, great for preserving a lost wallet for a half-century). Still, changes in the region can impact more populated parts of the world in ways that go beyond rising sea levels.

For example, the polar vortex over Antarctica, a wind pattern driven by the contrast between the frigid pole and the warmth at lower latitudes, can impact temperatures and rainfall patterns in Australia; a weakened polar vortex can induce hot and dry extremes there.

There are a number of things just about anyone can do to help blunt the effects of climate change on Antarctica and the rest of the world, ranging from flying less to eating less meat. If we manage to cut emissions and hold warming to 2°C above pre-industrial levels, sea level rise by the end of this century could be just half of what it would be otherwise.

Source: "Four decades of Antarctica Ice Sheet mass balance from 1979-2017" Proceedings of the National Academy of Sciences, Jan. 2019. Image: World Economic Forum
Source: “Four decades of Antarctica Ice Sheet mass balance from 1979-2017” Proceedings of the National Academy of Sciences, Jan. 2019. Image: World Economic Forum.

The notion of ice melt in Antarctica contributing to sea level rise isn’t merely theoretical. A study published in 2019 estimated that a six-fold increase in yearly ice mass loss in Antarctica caused global sea levels to rise by more than half an inch between roughly the time Margaret Thatcher became prime minister in the UK, and Emmanuel Macron became the president of France.

For more context, here are links to further reading from the World Economic Forum’s Strategic Intelligence platform:

  • Scientists turned to seals for that Antarctic glacial meltwater study because harsh winter conditions limit the use of ships or planes to make observations, according to this report. Seven southern elephant seals and seven Weddell seals were deployed. (Science Daily)
  • The discovery of life 900 metres beneath Antarctic ice was an accident, according to this report – researchers had drilled a borehole in search of sediment samples, and instead found 13 sponges and 22 unidentifiable “stalked organisms.” (Big Think)
  • Australia’s plans to build an airport with a 2.7-kilometre paved runway in eastern Antarctica is deemed controversial, according to this report – due to its potential environmental impact, and “major” geopolitical concerns. (The Diplomat)
  • A recent study found that the West Antarctic Ice Sheet has declined steadily, as expected, but the East Antarctic Ice Sheet is far more sensitive to spikes in the weather than thought – which could make modelling of sea level rise more accurate, according to this report. (Eos)
  • This piece argues that preventive measures have to be taken to limit the impacts of climate change, tourism, fishing, and research infrastructure on the western Antarctic Peninsula – before it’s too late. (Nature)
  • According to this report, the ability of waves to transport large microplastics faster than previously thought helps us understand why they’re now found throughout the ocean – including around Antarctica. (The Conversation)
  • Turns out we may have had it all wrong when it comes to melting icebergs. This study found that while current models assume they melt uniformly, they actually do so at different speeds based on shape – a discovery that could help better assess climate change. (Science Daily)

On the Strategic Intelligence platform, you can find feeds of expert analysis related to AntarcticaClimate Change and hundreds of additional topics. You’ll need to register to view.

Team Visits Thwaites Glacier

The Thwaites Glacier, also referred to as the Doomsday Glacier, is closely watched for its potential to raise sea levels. Along with Pine Island Glacier, it is part of the “weak underbelly” of the West Antarctic Ice Sheet, due to vulnerability. This hypothesis is based on both theoretical studies of the stability of marine ice sheets and observations of large changes on these two glaciers. In recent years, both glaciers have retreated and melted at an alarming rate.

For years, scientists have watched the Thwaites Glacier from a distance, but in November 2019, a team set out to investigate what is happening below.